Wellhead assemblies



Aug. 23, 1966 w. w. WORD, JR 3, 3

WELLHEAD AS SEMBLIES Filed Aug. 19, 1963 6 Sheets-Sheet INVENTOR William W. Word,Jr.

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ATTORNEY5 Aug. 23, 1966 w, w, WORD, JR 3,268,243

WELLHEAD ASSEMBLIES Filed Aug. 19, 1963 6 Sheets-$heet 2 INVENTOR William W. Word,J r.

ATTORNEYS Aug. 23, 1966 w. w. WORD, JR

WELLHEAD ASSEMBLIES 6 Sheets-Sheet FIG.5.

Filed Aug. 19, 1963 INVENTOR William W. Word,Jr.

M, zu

ATTORNEYS FIG.4.

Aug. 23, 1966 w, w, D, JR 3,268,243

WELLHEAD ASSEMBLIES Filed Aug. 19, 1963 6 Sheets-Sheet FIG 6.

INVENTOR William W. Word,Jc

ATTORNEYS Aug. 23, 1966 Filed Aug. 19, 1963 6 Sheets-Sheet 5 Flam INVENTOR William W.Word,Jr.

ATTORNEYS 23, 1966 w. w. WORD, JR 3,268,243

WELLHEAD ASSEMBLIES Filed Aug. 19, 1963 6 Sheets-Sheet 6 INVENTOR William w.Word,Jr.

ATTORNEY 5 United States Patent 3,268,243 WELLHEAD ASSEMBLIES William W. Word, Jr., Houston, Tex., assignor to Armco Steel Corporation, Middletown, Ohio, a corporation of Ohio Filed Aug. 19, 1963, Ser. No. 302,974 9 Claims. (Cl. 285-142) This invention relates to wellhead apparatus and more particularly to wellhead assemblies installed at underwater locations remote from the floating vessel or like support from which drilling and completion of the well are accomplished.

In underwater wellhead installations, the problem of providing for return flow from the annulus about a casing string being cemented frequently presents severe difficulties arising both because of the need for physically accommodating the return flow within the wellhead and because of the requirement that the flow path for the return flow must be sealed after cementing of the casing has been completed. When the size of the casing hanger is adequate, it is sometimes possible to provide an annular series of ports through the hanger, so that, during cementing, the return fluid can flow upwardly through the hanger. In such cases, a remotely operated valve or other sealing device is used in conjunction with the hanger so that the ports can be sealed after the cementing operation has been completed. Wellheads employing such ported hanger arrangements are disclosed, for example, in copending application Serial Number 192,174, filed May 3, 1962, now Patent No. 3,171,489, by Charles M. Cole, Paul E. Bickel and William W. Word, Jr. Though the use of ported hangers is an advantageous and successful expedient, the space within the wellhead frequently does not allow the hanger to be provided with ports, so that some other approach to the problem must be adopted.

A general object of this invention is to provide an improved underwater wellhead assembly having provision for accommodating the return flow during cementing of a casing string.

A further object is to devise an underwater wellhead construction wherein the return flow during cementing of a casing string is conducted around the casing hanger via a by-pass flow duct or ducts arranged outside of the passage in which the hanger is situated, the arrangement being such that, after completion of the cementing operation, the by-pass can be sealed off simply and effectively by an internal wellhead member, such as a sleeve or a second hanger, disposed above the casing hanger.

Another object is to provide an especially simple and effective underwater wellhead assembly of the type described which employs only a single wellhead body member for suppporting and sealing the surface casing and all casing and tubing strings disposed inwardly of the surface casing.

A still further object is to provide a wellhead assembly of the type described wherein the need for remotely operated valves or the like for sealing off the flow ducts for the return flow after cementing is avoided.

Yet another object is to devise a wellhead assembly of the type described which embodies only internal elements which can be easily landed and require no special manipulation to accomplish, for example, the closing off of the flow ducts used during cementing.

In order that the manner in which these and other objects are attained in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a vertical sectional view of awellhead assembly being shown as completed through landing of the hanger for the surface casing;

FIG. 2 is a transverse sectional view taken on line 22, FIG. 1;

FIG. 3 is a view, partly in vertical section and partly in vertical elevation, of a casing hanger employed in the assembly of FIG. 1;

FIG. 4 is a view, similar to FIG. 1, showing the assembly completed through landing of the hanger for the intermediate casing string;

FIG. 5 is a transverse sectional view taken on line 55, FIG. 4;

FIG. 6 is a view, partly in vertical section and partly in vertical elevation, of a sealing sleeve employed, as shown in FIG. 4, for closing of the flow duct provided to accommodate return flow during cementing of the surface casing;

FIG. 7 is a view, similar to FIG. 1, showing the assembly completed through hanging of the tubing string; and

FIG. 8 is a vertical sectional View of a wellhead assembly constructed in accordance with another embodiment of the invention.

Referring now to the drawings in detail, FIGS. 1-7 thereof illustrate a remotely installed underwater wellhead assembly characterized by provision of by-pass flow ducts, external to the through passage of the wellhead, for accommodating return flow during cementing of the surface casing, the by-pass flow ducts being closed after the surface casing has been cemented, by a loadbearing seal sleeve which supports the hanger for the intermediate casing. As seen in FIG. 1, the assembly includes a base structure comprising a landing plate 1 seated on outer casing 2 and rigidly carrying a stub body 3 from which the conductor casing 4 depends.

Seated on the base structure and rigidly clamped and sealed to body 3 is an elongated upright body member 5 having an upright passage indicated generally at 6. Body 3 has a flat transverse annular upper end face 7 and a peripheral flange 8. The lower end of body member 5 has a flat transverse annular face 9, which directly engages face 7, and a peripheral flange 10. Body member 5 is secured by a conventional ring clamp 11 engaging flanges 8 and 10. Body 3 has a central passage 12 with which passage 6 is aligned, passage 12 being surrounded by an annular projection defined by the wall of the passage and a downwardly and outwardly slanting frusto-conical surface 13. At its lower end, body member 5 has a downwardly opening recess defined by a downwardly and outwardly slanting surface 14 which is slightly larger than and concentric with surface 13, surfaces 13 and 14 converging downwardly. A metal sealing ring 15 of such trapezoidal cross-section as to be wedged between surfaces 13 and 14 under the axial clamping force applied by clamp 11, is disposed between the two frusto-conical surfaces.

Passage 6 is cylindrical and includes a short lower portion 16 and an elongated upper portion 17, portion 17 being of slightly larger diameter than is portion 16. The two passage portions are joined by a transverse annular upwardly directed shoulder 18 which serves as a seat for rigidly supporting the casing hanger 19 against downward movement.

Described in detail and claimed in copending application Serial Number 302,994, filed concurrently herewith by Edward E. Castor, Claude R. Neilon, Michael A. Walker, and William Word, In, casing hanger 19 comprises a tubular mandrel body 20 having an intermediate, larger diameter portion 21, dimensioned to fill passage portion 17, and an elongated dependent portion. 22 including an exteriorly threaded lower end 23 of smaller outer diameter and a portion 24 of intermediate outer diameter, all of portion 22 being dimensioned to pass freely into passage portion 16 with a substantial annular space being left between the wall of passage portion 16 and mandrel body portion 24. A metal ring 25 slidably embraces the right cylindrical outer surface of portion 24, being retained generally in place by a snap ring 26 and held initially, in a lower position, by shear pins 27 which project inwardly to engage in an outwardly opening transverse annular groove in mandrel body portion 24. The main body of ring 25 presents an outer cylindrical sur face of such diameter as to substantially fill passage portion 17, and terminates at its lower end in a transverse annular downwardly and inwardly slanting frusto-conical shoulder 28 adapted to come into flush engagement with shoulder 18 as the hanger is landed. Below shoulder 28, ring 25 is dimensioned to fit slidably within passage portion 16.

The upper end portion of ring 25 includes an upwardly extending annular projection 29 defined by an inner cylindrical surface 30, a flat transverse annular end face 31, and a downwardly and outwardly slanting frusto-conical outer surface 32, the root of surface 32 being spaced inwardly from the outer surface of the main body of the ring so that an upwardly directed transverse annular shoulder 33 surrounds the base of the projection. The lower end portion of mandrel body part 21 is similarly formed with a downwardly extending projection 34 of the same dimensions and configuration as projection 29 but arranged in opposition thereto. Thus, projection 34 includes inner cylindrical surface 35, end face 36 and outer frusto-conical surface 37, the latter terminating at transverse annular shoulder 38.

With shear pins 27 in place, ring 25 is disposed with projection 29 spaced a substantial distance below projection 34, so as to accommodate the weight-actuated, pressure-energized seal indicated generally at 39. The seal includes a metal ring 40 which slidably embraces the outer surface of intermediate portion 24 of the mandrel body, the upper and lower ends of ring 40 being dimensioned to be received within the annular spaces enclosed by projections 29 and 34. Securely afiixed to the outer surface of ring 40, as by being molded directly thereon, is a flexible lip-type annular gasket 41 of synthetic rubber or like material. Gasket 41 includes a downwardly projecting lip 42 and an upwardly projecting lip 43.

Assuming ring 25 to be retained by shear pins 27 in the position seen in FIG. 3, surfaces 32 and 33 are spaced apart by such a distance as not to be engaged by lips 42, 43, so that the lips of the gasket can assume their normal or relaxed positions. Under these circumstances, the lips 42, 43 slant inwardly, with the outer surface 44 of the central portion of the gasket having essentially the same diameter as the outer surfaces of ring 25 and mandrel portion 20, so that, as the hanger descends toward seat 18, the gasket will not be stripped off. In this connection, it is to be noted that shear pins 45 retain ring 40 in centered position between ring 25 and mandrel body portion 21.

To install the hanger and suspend the surface casing 46, a handling tool 47 is connected to the hanger, as by the interior threads 48, FIG. 3, and handling string 49 is manipulated to lower the casing string and hanger until shoulder 28 engages shoulder 18. Further downward movement, resulting from the weight of the casing string, ruptures shear pins 27 and 45, causing relative telescopic movement between ring 25 and seal 39, on the one hand, and the mandrel body 20, on the other, until complete metal-to-metal contact is established between body portion 21, ring 40 and ring 25. As a result, the surface casing string is suspended from shoulder 18 via only metal parts of the hanger. As mandrel body is forced downwardly, the axial spacing between ring 25, ring 40 and body portion 21 is eliminated, so that surfaces 32 and 37 move under gasket lips 42, 43, respectively, the tapered form of the surfaces 32, 37 causing the lips to be forced outwardly into uniform engagement with the adjacent wall of passage portion 17, as seen in FIG. 1. With the lips of the gasket so disposed, a pressure differential axially across the seal will cause the gasket to be pressure energized into good sealing engagement with the surrounding wall of the passage.

In a location always surrounded by metal ring 40, mandrel body portion 24 is provided with an outwardly opening transverse annular groove in which is disposed a suitable pressure energized packing ring 50 which serves to establish a fluid-tight seal between ring 40 and the mandrel body.

At an appropriate distance above shoulder 18, body member 5 is provided with a transverse annular inwardly opening groove 51. Mandrel body portion 21 is provided with an outwardly opening groove 52 slidably accommodating a plurality of arcuate locking segments 53 each urged outwardly by spring 54, FIG. 3. When the hanger 19 is fully landed, with shoulders 18 and 28 in engagement and ring 25, ring 40 and mandrel body portion 21 in mutual engagement, groove 52 opens toward groove 51, so that segments 53 can snap outwardly, engaging in groove 51 and locking the hanger against movement upwardly away from shoulder 18. As fully disclosed in copending application Serial Number 302,836, filed concurrently herewith by Robert Bishop, Edward E. Castor, Michael A. Walker and William W. Word, Jr., a sleeve 55, normally held in inactive raised position by shear pins 56, is provided to accomplish retraction of segments 53, for retrieval of the hanger, when the sleeve is forced downwardly by a suitable tool into camming engagement with downwardly and outwardly slanting faces 57 of the segments.

At the bottom of body member 5, mandrel body portion 22 is spaced a material distance inwardly from the wall of passage portion 16, so that the annulus about the surface casing string 46 is in direct communication with the interior of body member 5 below the casing hanger. In the area just below shoulder 18, body member 5 is provided with a plurality of ports 58 which are spaced in a circular series and each slant upwardly and outwardly from passage portion 16. In an area above the position assumed by the top of hanger 19 when the hanger is fully landed, body member 5 is provided with a plurality of ports 59 each slanting downwardly and outwardly from passage portion 17, the number of ports 59 being equal to the number of ports 58 and respective ones of the ports 58 and 59 being aligned vertically with each other. Each port 58 is connected to the corresponding one of ports 59 by an arcuate conduit 60 which is welded at its ends to the outer surface of the body member. Thus, ports 58 and 59 and conduits 60 serve to complete by-pass flow ducts which extend wholly outside of passage 6 and provide free communication between the annular space surrounding the surface casing string below hanger 19 and the annular space surrounding the handling string 49 above the hanger.

From FIG. 1, it will be clear that the exterior bypass flow ducts freely pass the return flow during cementing of the surface casing string without interfering in any way with the functions of the casing hanger and despite the fact that there is a full and direct seal between the casing hanger and the wall of passage portion 17.

After the surface casing string has been cemented, the handling joint 49 is manipulated to break the threaded connection between handling tool 47 and the casing hanger 19, and the handling string and tool 47 are withdrawn. To simplify breaking this connection, the threads at 48 are left-handed threads and a suitable stop (not shown) is provided to prevent rotation of the casing hanger. Assembly of the internal elements of the wellhead is now continued, as well be clear from FIG. 4.

Employing a suitable handling tool (not shown), the sealing device 65, shown in detail in FIG. 6, is landed and actuated to the condition seen in FIG. 4. Referring to FIG. 6, it will be seen that the sealing device 65 comprises a main tubular body 66 having an upper portion 67 and a dependent elongated lower portion 68. Portion 67 has an outer right cylindrical surface 69 of such diameter that the upper body portion substantially fills passage portion 17. Lower body portion 68 presents a right cylindrical outer surface 70 of substantially smaller diameter than is surface 69. Slidably embracing lower body portion 68 are an upper seal ring indicated generally at 71, an intermediate metal ring 72, a lower seal ring, indicated generally at 73, and a lower metal ring 74.

At its lower end, the upper portion of body portion 67 is provided with a downwardly extending annular projection 75 defined by an inner cylindrical surface 76, a flat transverse annular end face 77, and a downwardly and inwardly slanting frusto-conical outer surface 78, the root of projection 75 being spaced inwardly from surface 69 so that a transverse annular shoulder 79 is presented at the upper edge of surface 78. Projection 75 is spaced outwardly from surface 70, so that there is an intervening flat annular transverse surface 80 at the upper edge of surface 76.

At its upper end, ring 72 is formed with an upwardly extending annular projection 81 defined by cylindrical inner face 82, flat transverse end face 83, and upwardly and inwardly slanting frusto-conical outer surface 84, shoulder 85 being presented at the base of surface 84 and transverse annular surface 86 extending inwardly from the bottom edge of surface 82. Projections 75 and 81 have the same dimensions but are opposed to each other. Thus, for example, cylindrical surfaces 76 and 82 have the same diameter and are coaxial.

Seal ring 71 includes an inner metal ring 87, the inner surface of which embraces surface 70 and the upper and lower ends of which are dimensioned to be received within the spaces surrounded by surfaces 76 and 82, respectively. Thus, upper face 88 of ring 87 can come into direct flush engagement with surface 80, and lower face 89 can come into flush engagement with surface 86. The outer face of ring 87, suitably interrupted by grooves as shown, is of substantially smaller diameter than surface 69. Sealing element 90, of synthetic rubber or the like, has a main body 91 which is molded directly on metal ring 87 and which presents an outer surface 92 of essentially the same diameter as surface 69. Resiliently flexible lips 93 and 94 extend respectively upwardly and downwardly from body 91, each lip normally tapering toward the corresponding one of surfaces 78 and 84 when the sealing element is relaxed. Thus, in relaxed condition, lip 93 presents an upwardly and inwardly tapering outer surface 95, and lip 94 presents a downwardly and inwardly tapering surface 96. The inner surface of lip 93 is cylindrical adjacent ring 87 and curves outwardly to tip 97, as shown. The inner surface of lip 94 similarly curves outwardly to tip 98.

Ring 87 and ring 72 are initially retained, by shear pins 99 and 100, respectively, in positions on body portion 68 such that seal ring 71 is spaced downwardly from body portion 67, with seal lip 93 held out of engagement with surface 78, and ring 72 is spaced downwardly from seal ring 71, with lip 94 held out of engagement with surface 84.

At its lower end, ring 72 has a downwardly extending annular projection 101 which is identical with projection 75. Ring 74 has, at its upper end, an upwardly extending annular projection 102 identical with projection 81. Seal ring 73 is identical with seal ring 71, presenting lips 103 and 104. Seal ring 73 and metal ring 74 are initially retained on body portion 68, by shear pins 105 and 106, respectively, in axially spaced positions such that lip 103 is held out of contact with projection 101 and lip 104 is held out of contact with projection 102, as shown.

Ring 74 depends cylindrically below the end face 107 of body portion 68 and terminates in an inwardly projecting annular flange 108 which presents a flat, transverse, annular end face 109 dimensioned to engage the upper end face of body 20 of casing hanger 19 in the manner seen in FIGS. 4 and 7.

Above ports 59, body member 5 is provided with an inwardly opening transverse annular groove 110. Body portion 67 of sealing device 65 has a plurality of outwardly opening recesses 111 spaced in a transversely extending circular series, each recess 111 retaining an outwardly spring-biased shear pin 112 constructed in accordance with copending application Serial Number 302,973, tiled concurrently herewith by Edward E. Castor and Michael A. Walker. The axial disposition of recess 111 on body 66 is such that, when the sealing device has been lowered to bring face 109 into engagement with the top of the mandrel body 20, and adequate downward force is then applied to body 66 to rupture shear pins 99, 100, and 106 and bring elements 67, 87 and 72, the metal ring of sealing ring 73, and ring 74 all into mutual metal-'to-metal contact, the recesses 111 will open toward groove and the shear pins 112 will snap outwardly to engage in groove 110 and latch sealing device against upward movement away from casing hanger mandrel 19. Engagement of the shear pins 112 in groove 110 also serves to maintain the series metaLto-metal engagement between body portion 67, ring 87, ring 72, the metal ring of seal ring 73, ring 74 and the upper end of the body of mandrel 19, the latter being fixed rigidly against downward movement by engagement with shoulder 18.

As discussed in detail in aforementioned application Serial Number 302,994, the specific sealing device of FIG. 6 is particularly advantageous because, since lips 93, 94 and 103, 104 of the sealing elements lie in positions spaced inwardly from surface 69, there is no tendency for the resilient sealing elements of rings 71 and 73 to be stripped away by contact with the wall of passage 6, for example, as the sealing device is lowered into place. By comparing FIGS. 4 and 6, it will be clear that full weight actuation of the sealing device 65, to bring the movable parts thereof into metal-to-metal contact, causes surfaces 78 and 84 to urge lips 93 and 94, respectively, outwardly into contact with the surrounding wall of passage portion 17, so that occurrence of a fluid pressure differential axially across element 91 in either direction will cause pressure energization of the element against the surrounding passage wall to assure a good fluid-tight seal. Similarly, the outer surfaces of projections 101 and 102 urge the respective lips 103 and 104 of the sealing element of ring 73 outwardly into engagement with the surrounding wall of passage portion 17, so that formation of a fluid-tight seal here by pressure energization is assured.

Referring to FIG. 4, it will be seen that, when sealing device 65 has been fully landed and weight-actuated, seal ring 71 is located above ports 59 while seal ring 73 is disposed below ports 59. Accordingly, sealing device 65 serves to seal oh" the upper ends of the by-pass flow ducts, preventing further fluid flow from the space surrounding surface casing 46.

In locations surrounded respectively by the rings 71 and 73 after sealing device 65 has been weight-actuated body portion 68 is provided with outwardly opening grooves in which are retained pressure energized sealing rings 113 and 114 which serve to prevent fluid flow axially along surface 70.

Since it may be desirable to recover sealing device 65 from the wellhead, it is necessary to provide means for retaining the movable elements 71, 72, 73 and 74 on body portion 68 after the shear pins have been ruptured. For this purpose, a dependent cylindrical member 115 is provided, the upper edge thereof being connected to the lower end of body portion 68, as by a bayonet joint, and the lower end having an outwardly project- 7 ing flange 116 engaged beneath surface 109 when ring 74 is in its initial position.

At its upper end, body portion 67 presents shoulder means on which the mandrel 117 for suspending the intermediate casing string 118 is landed. This shoulder means includes an upper, downwardly and inwlardly slanting frusto-conical surface 119 and a lower, flat, transverse annnular surface 120, surfaces 119 and 120 being joined by a cylindrical surface 121. As will be clear from FIGS. 4 and 5, mandrel 117 has a main body portion provided with a downwardly and inwardly slanting shoulder 122 and a flat bottom face 123 for engagement with shoulders 119 and 120, respectively. Body is provided with a groove 124 disposed above the upper end of sealing device 65, when the latter has been landed, actuated and latched in place. Mandrel 117 has a plurality of outwardly opening recesses disposed to face groove 124 when the mandrel is seated, as shown in FIG. 4, each such recess retaining an outwardly biased shear pin 125 in such fashion that, when the mandrel 117 reaches its proper position, shear pins 125 engage in groove 124 to latch the mandrel against upward movement.

Mandrel 117 includes a centrally disposed dependent tubular portion 126 which is suitably threaded at its lower end for connection to casing string 118. Since portion 126 has the same diameter as the casing string to which it is connected, the main body portion of the mandrel projects laterally from portion 126 and occupies a substantial space at the upper end of the annulus around casing 118. Accordingly, mandrel 117 can be ported to accommodate the return flow which occurs during cementing of casing 118. Thus, a plurality of grooves or notches 127 are cut in the main body of mandrel 117, each groove or notch extending completely through the mandrel body portion so as to place the annulus around casing 118 in direct communication with the space above mandrel 117.

It will be understood that landing of mandrel 117 can be accomplished by means of a handling tool 128 and handling string 129, FIG. 4.

From FIG. 4, it will be noted that the sealing device 65, which effectively closes the bypass flow ducts defined by ports 58, 59 and conduits 60, acts as a load bearing element, directly supporting mandrel 117 and the weight of casing string 118.

With cementing of casing 118 completed, and handling joint 128 and string 129 removed, assembly of the internal elements of the wellhead is finished in the manner seen in FIG. 7. It will be seen thatmandrel 117 includes an upwardly projecting tubular portion 130 having a cylindrical outer surface spaced a material distance inwardly from the wall of passage portion 17. A seal device 131, described in detail and claimed in aforementioned copending application Ser. No. 302,994 is inserted downwardly into passage portion 17 until the lower end portion of the sealing device enters the annular space about mandrel portion 131 and engages the upper surface of the main body portion of the mandrel. Device 131 includes an outer pressure energized sealing ring 132 disposed to engage the wall of passage portion 17, and an inner pressure energized sealing ring 133 disposed to engage the outer surface of mandrel portion 130. Body member 5 is provided with a transverse annular inwardly opening groove disposed to receive latching segments 134 carried by seal device 131 so that the seal device, once landed on mandrel 117, is latched against upward movement.

The tubing string 135 is suspended from a hanger, indicated generally at 136, which is supported by seal device 131. Hanger 136 has a main body 137 having a dependent cylindrical portion 138 slidably embraced by portion ring 139. Ring 139, initially retained in a lower position by shear pins, cooperates with a seal ring 140 in the same general fashion hereinbefore explained with reference to o casing hanger 19, seal ring 1411 establishing a pressure energized seal between hanger 136 and the wall of passage portion 17. Ring 139 presents a downwardly directed transverse annular face which engages the upper end of seal device 131 when hanger 136 is landed. Ports 141 in ring 139 are effective to place the space between tubing and casing 118 in communication with a lateral flow duct 142.

Elements of the wellhead installed above body member 5 have been ignored in the foregoing description, since the nature of such elements is not pertinent to this invention. In general, however, the blow out preventers and Christmas tree are secured to the top of body member 5 by a remotely actuated coupling such as that described and claimed in copending application Ser. No. 264,195, filed March 11, 1963 by Claude R. Neilon, Michael A. Walker and William W. Wood, J r. It will be understood that the elements of the base structure, and body member 5, are assembled with the aid of a suitable guide system (not shown) which can be of the type described in US. Pat. No. 2,808,229, issued Oct. 1 1957, to Robert F. Bauer et al. and that the internal components of the wellhead usually are installed via a riser pipe extending from the wellhead to the surface of the body of water in which the installation is being made.

FIG. 8 illustrates another embodiment of the invention. Here, the wellhead assembly includes a base structure indicated generally at and comprising a relatively thick, weighted base plate 151 resting on the marine floor and having a central opening which accommodates the outer or conductor casing 152. The upper end of conductor casing 152 is thickened and provided with an outwardly directed peripheral flange 153 presenting a relatively broad, fiat transverse annular top face 154.

The wellhead body member, indicated generally at 155, is tubular, presenting an upwardly extending passage 156, and has an outwardly flaring lower end portion 157 which is notched to provide a downwardly directed transverse annular face 158 dimensioned to seat directly on surface 154. Member 157 also includes a dependent cylindrical skirt 159 which embraces flanges 153 and is provided with an inwardly opening groove accommodating an annular series of latching segments 16% which are engaged beneath flange 153 to secure body member to the top of the conductor casing.

Passage 156 includes a lower right cylindrical portion 161, an intermediate cylindrical portion 162, and an elongated upper cylindrical portion 163. Portions 161 and 162 are joined by a downwardly and inwardly slanting frusto-conical shoulder 164. Portions 163 and 162 are joined by a downwardly and inwardly slanting frustoconical shoulder 165. Accordingly, passage portion 161 is of smaller diameter, passage portion 162 is of intermediate diameter, and passage portion 163 of larger diameter.

At a point well below shoulder 164, body member 155 is provided with a radially outwardly extending port 166. At a point well above shoulder 165, body member 155 is provided with a radially outwardly directed port 167. A lower by-pass flow duct, indicated generally at 168, is completed by an elbow 169, threadedly engaged in port 166, pipe 170, check valve 171, pipe 172, and upper elbow 173 threaded into port 167.

An intermediate casing string 174 is suspended from a casing hanger mandrel 175 seated directly on shoulder 164. Mandrel 175 is landed by manipulation of a handling string (not shown) and is latched against upward movement away from shoulder 164 by means of a plurality of shear pins 176 engaged in a suitably disposed groove in passage portion 162. Mandrel 175 completely fills passage portion 162 above shoulder 164 and a fluid-tight seal is provided between the wall of passage portion 162 and mandrel 175, as by sealing elements 177. Accordingly, as the casing string 174 is cemented, the return fiow upwardly around the casing is blocked by mandrel 175.

This return flow can, however, reach the annular space above mandrel 175 and defined at this stage by the handling string, via the by-pass flow duct 168. When cementing of the casing string 174 is completed, the space around the casing is effectively isolated from the area of the wellhead assembly above mandrel 175 because of the automatic closing of check valve 171.

The handling string for mandrel 175 having been removed, a hanger member 178 is inserted downwardly into passage portion 163, seating directly upon the upper end of mandrel 175. Mandrel 178 completely fills passage portion 163 in an area spaced above mandrel 175 and is provided with two sealing elements 179 and 180 located respectively above and below port 167 so that this port is efi'ectively sealed off once the hanger member 178 has been landed. Hanger member 178 is latched against upward movement by means of a plurality of latching segments 181 engaged in a suitably disposed inwardly opening transverse annular groove in the wall of passage portion 163. Above the location of latch segments 181, the outer diameter of hanger member 17 8 is reduced, providing an annular space 182 between the wall of passage portion 163 and the hanger member 178.

The lower end portion of hanger member 178 is of reduced diameter, providing an annular space 183 immediately above shoulder 165. Generally radially extending grooves 184 are cut in the lower end portion of hanger member 178 so that space 183 is placed in communication with the through bore of hanger member 175 and, there fore, with the space within casing 174. Immediately above shoulder 165, body member 155 is provided with a radially disposed port 185. A second port 186 is provided in hanger member 155 at a location communicating with space 182. Ports 185 and 186 are interconnected by a by-pass flow duct indicated generally at 187 and constituted by elbow 188, check valve 189 and elbow 190. An additional port 191 is provided in body member 155 in a location communicating with space 182, and a lateral flow line 192 is connected to this port.

Hanger member 178 has an upright passage including a downwardly and inwardly slanting shoulder 193. An inner casing string 194 is suspended from hanger member 178 by mandrel 195. Mandrel 195 has, at its lower end, a downwardly and inwardly slanting frusto-conical shoulder 196 directly engaging shoulder 193, Above shoulder 193, mandrel 195 completely fills the passage of hanger member 178 and suitable sealing elements 197 are provided to seal between the mandrel and the hanger member.

Landing of mandrel 195 is accomplished by handling string 198 and, with the handling string still in place, cementing of casing 194 can be accomplished, with the return flow between casings 194 and 174 passing upwardly through mandrel 175, the ports formed by grooves 184, space 183, and by-pass flow duct 187 into the space 182. The return flow can then be directed either upwardly, within a suitable riser pipe (not shown) or outwardly via lateral flow duct 192.

In this embodiment of the invention, it will be observed that the external by-pass flow duct 168 serves essentially the same purpose as the external by-pass flow ducts provided by ports 58, 59 and conduits 60. Thus, just as the space available for hanger 19, FIG. 7, is too small to allow that hanger to be ported, the space available for hanger mandrel 175, FIG. 8, does not allow porting of that mandrel. An important characteristic feature of the embodiment of FIG. 8 is that the external by-pass flow duct indicated at 168- is closed and sealed not only by the action of check valve 171 but also by hanger member 178 and its sealing elements 179 and 180.

While two advantageous embodiments of the invention have been chosen to illustrate the same, it will be obvious that various changes and modifications therein can be made without departing from the scope of the invention defined by the appended claims.

What is claimed is:

1. In an underwater wellhead assembly, the combination of wellhead body means adapted for upright installation on a suitable base structure and having an upright passage, and

transverse upwardly directed shoulder means;

casing hanger means disposed in said passage and supported by said shoulder means,

said hanger means filling said passage above said shoulder means,

said hanger means and said body means cooperating to effect a seal against upward flow of fluid around said hanger means;

means carried by said body means and defining at least one by-pass flow duct exterior to said passage and communicating between a point in said passage below said hanger means and a point in said passage above said hanger means; and

a load-bearing tubular internal wellhead member supported in said passage above said hanger means and sealed to said body means to prevent fluid flow through said by-pass flow duct.

2. A well head assembly in accordance with claim 1 and wherein said internal wellhead member is seated on said hanger means.

3. A wellhead assembly in accordance with claim 1 and wherein said internal wellhead member is a seal device comprising two external packings disposed respectively above and below the upper end of said by-pass flow duct.

4. A wellhead assembly in accordance with claim 3 and further comprising second hanger means disposed above said seal device and seated thereon.

5. A wellhead assembly in accordance with claim 1 and wherein said internal wellhead member is a hanger member.

6. A wellhead assembly in accordance with claim 5 and wherein said hanger member is seated on said casing hanger means.

7. In a underwater wellhead assembly, the combination of a base structure having an opening;

a wellhead body member rigidly secured to said base structure and extending upwardly therefrom, said body member having an upright passage aligned with said opening, and

a transverse annular upwardly directed shoulder;

a casing hanger comprising a tubular hanger body having an upper portion dimensioned to fill said passage above said shoulder and a lower portion dimensioned to depend in said passage below said shoulder,

a weight-actuated packing surrounding said lower portion and seated on said shoulder, said packting providing a seal against upward flow of fluid around said casing hanger, and

means latching said hanger body to said body member to prevent upward movement of said hanger away from said shoulder;

means carried by said body member and defining at least one by-pass flow duct exterior to said passage and communicating between a point in said passage below said casing hanger and a point in said passage above said casing hanger; and

a load-bearing tubular internal wellhead member supported in said passage above said casing hanger and sealed to said body member to prevent fluid flow through said by-pass flow duct.

8. A wellhead assembly in accordance with claim 7 and wherein '1 i. said hanger body has an upwardly directed upper end face, and said load-bearing tubular internal wellhead member is a sealing sleeve disposed in said passage above said casing hanger and seated on said upper end face, said sleeve comprising exterior packing rings disposed respectively above and below the upper end of said by-pass flow duct and sealing between said sleeve and said body member, and

means latching said sleeve to said body member to prevent upward movement of said sleeve,

9. In wellhead apparatus for installation under water, the combination of a unitary wellhead body adapted for upright installation on a suitable base structure and having an axial through bore,

a transverse annular internal shoulder which faces upwardly when said body is in upright position, and

two lateral ports extending through the wall of said body and communicating with said bore, one of said ports being located above said internal shoulder and the other of said ports being located below said internal shoulder;

a casing hanger adapted for downward insertion into said bore and having a transverse annular outer shoulder adapted to seat on said internal shoulder of said body,

an upper portion dimensioned to substantially fill 3 the portion of said bore immediately above said internal shoulder when said shoulders are engaged, and a lower portion having a significantly smaller transverse cross-section than does the portion of said bore below said internal shoulder, said outer shoulder of said hanger being located between said upper and lower portions; a by-pass conduit located exteriorly of said body and fixed rigidly thereto, one end of said conduit communicating with one of said ports and the other end of said conduit communicating with the other of said ports; and a load-bearing tubular internal wellhead member supported in said bore above said casing hanger and sealed to said body to prevent fluid flow through said by-pass conduit.

References Cited by the Examiner UNITED STATES PATENTS 2,094,812 10/1937 Penick 16687 2,623,467 12/1952 Andrew 285-133 X 3,084,745 4/1963 Floyd 16689 3,134,610 5/1964 Musolf 285133 X 3,151,680 10/1964 Parkhurst 285133 3,165,175 11/1964 Johnson 16689 X 3,163,220 12/1964 Haeber 16666.5 3,216,731 11/1965 Dollison 277-1 CARL W. TOMLIN, Prz'mmy Examiner.

S. R. MILLER, R. GIANGIORGI, Assistant Examiners. 

1. IN AN UNDERWATER WELLHEAD ASSEMBLY, THE COMBINATION OF WELLHEAD BODY MEANS ADAPTED FOR UPRIGHT INSTALLATION ON A SUITABLE BASE STRUCTURE AND HAVING AN UPRIGHT PASSAGE, AND TRANSVERSE UPWARDLY DIRECTED SHOULDER MEANS; CASING HANGER MEANS DISPOSED IN SAID PASSAGE AND SUPPORTED BY SAID SHOULDER MEANS, SAID HANGER MEANS FILLING SAID PASSAGE ABOVE SAID SHOULDER MEANS, SAID HANGER MEANS AND SAID BODY MEANS COOPERATING TO EFFECT SEAL AGAINST UPWARD FLOW OF FLUID AROUND SAID HANGER MEANS; MEANS CARRIED BY SAID BODY MEANS AND DEFINING AT LEAST ONE BY-PASS FLOW DUCT EXTERIOR TO SAID PASSAGE AND COMMUNICATING BETWEEN A POINT IN SAID PASSAGE BELOW SAID HANGER MEANS AND A POINT IN SAID PASSAGE ABOVE SAID HANGER MEANS; AND A LOAD-BEARING TUBULAR INTERNAL WELLHEAD MEMBER SUPPORTED IN SAID PASSAGE ABOVE SAID HANGER MEANS AND SEALED TO SAID BODY MEANS TO PREVENT FLUID FLOW THROUGH SAID BY-PASS FLOW DUCT. 